Hello everyone ,
I love explaining about my knowledge in Biology because i am medical student :) & this is my first post related to science.Hope you will have a feel that you learned something today :) .
so lets get started ,
Introduction :-
Every day we are exposed to a large number of infection agents . However only a few of them results in diseases .why ? It is due to the fact that the body is able to defend itself from most of them . The overall ability of an individual to fight against the disease causing organisms is called Immunity.
- The network of organ cells & proteins that protect the body from harmful infection agents such as Bacteria,Viruses,Animal parasites,Fungi etc., is called the Immune system.
- The basic requirement of the immune system is to differentiate between self and non self & to protect the body from Harmful foreign substances,Micro-organisms,Toxins & Malignant cells etc.,
Concepts of Immunology :-
To understand Immunology better,we have to know certain basic concepts such as lines of defence,Cells,Organs & Soluble mediators of the immune system , antigens , types of immunity , mechanism of immunity & Immunological Disorders .
lines of defence in body :-
First line of defence :
Whenever bacteria , viruses , Fungi and parasites try to enter the body of an organism , skin , mucous membranes & the Enzyme Lysozyme of saliva , tears etc., present their body .
Second line of defence :-
If the microorganisms cross 1st line of defence & enter the body ,the phagocytes,Natural killer cells,Antimicrobial substances, inflammation, fever etc.,
Third line of defence :-
If the microbes cross even the 2nd line of defence , then the lymphocytes & antibodies fight against them . It is highly specific but takes several days to become fully functional.
Cells of the immune system :-
There are three types :-
Lymphocytes :-
These are the chief cells of the immune system ,which are of 3 types
- B-cells
- T-cells
- Larger Granular Lymphocytes (LGLs)
Based on the size , lymphocytes can also be divided into small & large Lymphocytes .Small Lymphocytes include B-cells & T-cells whereas the large lymphocytes include granular lymphocytes that consists of Natural killer cells(Nk-cells).
B-cells :-
- The lymphocytes capable of producing antibodies and can capture circulating antigens are called B-cells.
- They are produced by the "Stem cells" in the bone marrows of Adult mammals & Bursa of Fabricius in Birds.
Source
Mature B-cells synthesize various types of antibodies which are displayed on their Membrane surface . Also called as Immuno-competent B-cells.These mature Immuno-competent B-cells reach the secondary Lymphoid organs & develop into Functional Immune cells which later differentiate into "Long Lived " memory cells & Effector plasma cells .Plasma cells produce antibodies specific to the antigen to which they are exposed .Memory cells store information about the specific antigens & Show quick response when the same type of antigen invades the body again .
T-cells :-
The lymphocytes that are not capable of producing antibodies & cannot recognize the free/ circulating antigens are called T-cells .
- They are produced in the bone marrow reach the Thymus gland & differentiate into mature T-cells .
Source
Do you know ?
Through T-cells cannot recognize the free or circulating antigens , they can recognize antigens if presented by Antigen presenting cells(Apcs) or altered self cells by MHC molecules.APCs include dendritic cells , macrophages & B-lymphocytes .
Soluble mediators of Immunity :-
There are three types namely :
Complement proteins
These are a group of Inactive Plasma proteins & cell surface proteins.When activated they form a Membrane attack complex (MAC) that forms pores in the plasma membrane of the affected cells allowing ECF to enter the cells & make them Sell & Burst . Some of them form a coat on the surface of the pathogens & attract Neutrophils & Macrophages to phagocytes & them destroy them.
Cytokines
They are small,soluble Molecules secreted mostly by the Th cells or infected cells .They bid to cell surface receptors & initiate activation or differentiation of the cell of the immune system to stimulate Phagocytosis & cyclosis of the infected cells .
Antibodies ( Immunoglobins ):-
Whenever Pathogens enter our body , the B-cells produce an army of proteins called antibodies to fight with them .
- They are Highly specialized for binding with specific antigens.
- The part of an antibody that recognizes an antigen is called Paratope(Antigen binding site).
Based on this mobility,antibodies are of two types :
- Circulating (or)Free antibody
- Surface Antibody
The circulating are present in the body fluids whereas the surface antibodies are present on the surface of the mature B-cells as well as memory cells .
Structure of Antibody
The basic structure of an Antibody was proposed by "Rodney Porter". It is a 4-shaped molecule with 4 polypeptide chains of which two are long identical heavy chains (H) & two are small identical light chains(l).
Hence antibody is represented as H2L3... the two chains are linked by disulphide bonds .
Antibodies can come in different varieties known as isotypes .There are five antibody isotypes known as IgA, IgD, IgE, IgG, and IgM , each named with an "Ig" as prefix stands for immunoglobulin .
References :
keep going ! ilike it
Its informative actually,heard some of the things but not this much !!Made me feel like when I was learning things in school!!
Wow , Visit my blog daily you can recall everything related to science :P
Waw, this is educative and informative. Thanks for sharing this post. It will go a long way in helping people like me, lol.
Good job👍
You have a few errors in this post, and many things are over-simplified. Your source for "lines of defence" isn't even science related. It would be better to reference a source that explains the arms arms of the immune system and introduce innate (physical barriers and myeloid cells) versus adaptive immunity (lymphocytes and antigen presentation). Not "eater cells" and "smart cells".
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